A substrate storage container is generally provided with a container main body for storing a plurality of disc-shaped shape substrates such as semiconductor wafer in a parallel manner therein. A substrate transfer opening for transferring the disc-shaped substrate is formed in the container main body. Then, a lid body for sealing the substrate transfer opening is provided so as to be mounted in a detachable manner from outside to the substrate transfer opening.
In order to hold the disc-shaped substrate inside the container main body in a state without rattling, a back side supporting portion is disposed at a back side area inside of the container main body as seen from the substrate transfer opening, and a lid side retainer is provided at an inner wall portion of a lid body.
However, the lid side retainer does not enter a state of holding the disc-shaped substrate until the lid body is mounted to the substrate transfer opening of the container main body. For this reason, a substrate placement piece is provided for placing the disc-shaped substrate at an area proximal to the substrate transfer opening, during a state in which the lid body is not mounted. When the disc-shaped substrate enters a state held by the lid side retainer, the disc-shaped substrate is brought into a state floating from the substrate placement piece (for example, Japanese Unexamined Patent Application (Translation of PCT Publication), Publication No. 2003-522078; FIG. 10, etc.).